The Elf wrote:I'm struggling to understand its usage as a stereo mic beyond simply muting a pair of capsules?

The four tetrahedrally-mounted sub-cardioid mic capsules (A-format) that you see in the Rode mic have to be processed into the B-format by the associated software plugin. The B-format (which can be created directly with the right capsules, but is less practical) comprises three orthogonal fig-eights plus an omni, all coincident with each other -- in effect making three Mid-Side systems pointing in opposite directions (left-right, front-back, up-down).

These can then be combined with each other in clever ways to create any number of virtual mics with any desired polar patterns, pointing in any desired direction. So you can create a stereo array of crossed cardioids or hypercardioids or whatever, pointing in any desired direction -- hence it being an incredibly versatile stereo mic.

But you can go beyond that and create additional mics looking elsewhere to make a 5.1 array or whatever you want. It's also possible to manipulate the signals to create a kind of 'zoom' effect which goes some way to simulating the effect of moving the mic closer or farther away from the source. It's not quite the same thing, but it can be useful!

This is called a 'first order' ambisonic system. The clever people are now using 'higher-order ambisonics' (often shortened to HOA) which essentially creates lots more virtual mics in the B-format -- so 9 or 16 or 25 channels instead of 4, say -- and that allows for far more accurate signal processing and thus more accurate and stable sound images.

Ha! Did not know about that! I remember when I was in my teens a guy had a 5" OR tape of shantys and that was one of them. Such scattalogical stuff was not common then and as teenage blokes we of course thought it hilarious.

There was also a very blue tape going around of Jerry Lewis slagging off Dean Martin.

Hugh Robjohns wrote:These can then be combined with each other in clever ways to create any number of virtual mics with any desired polar patterns, pointing in any desired direction. So you can create a stereo array of crossed cardioids or hypercardioids or whatever, pointing in any desired direction -- hence it being an incredibly versatile stereo mic.

Interesting. It seems to me that a good way of seeing how useful the mic could really be without buying it first would be to install the Soundfield by Rode plugin and see if I could find and download example files to work with. It turns out there's stacks of them out there, just Google ambisonic files. It'll probably have to wait until after Christmas now but I'll report back on how I found it.

ConcertinaChap wrote:Interesting. It seems to me that a good way of seeing how useful the mic could really be without buying it first would be to install the Soundfield by Rode plugin and see if I could find and download example files to work with. It turns out there's stacks of them out there, just Google ambisonic files. It'll probably have to wait until after Christmas now but I'll report back on how I found it.

Ooo! Ooo! That sounds like fun! I have downloaded the zip file of the pluggin, do you know if it will run in Samplitude ProX 3?

Like you CC this will have to wait until after the crimble madness (got son coming and have to clear a room because someone is giving me a whole, pretty good hi fi rig including some quite large Mission speakers.)

AFAIK it should run in any DAW that supports quad tracks or busses. Note that it defaults to A-format, so if you're working with Ambisonic (B-format) material you need to change the input format appropriately.

Another interesting thing. I thought I'd download Surroundzone 2 for a play as well, however if you Google it the page at Soundfield.com just gives you 404 not found, so I wonder if it's been dropped now Soundfield by Rode is here.

No - I take it all back, ignore the preceding, they've just had a site reorganisation. :blush:

It's interesting that, although they do basically the same things, the original SoundField SurroundZone plugin and the new Rode equivalent do work in entirely different ways under the hood (the Rode version using much more sophisticated maths), and the resulting decoded virtual mics do sound noticeably different.

From Sam's review it seems that Soundfield by Rode suffers from epic latency while Surroundzone doesn't. Not a problem if you're field recording but if you're using the mic in the studio and you want the artists to hear themselves then it might well be worth having Surroundzone installed for that purpose if nothing else.

ConcertinaChap wrote:From Sam's review it seems that Soundfield by Rode suffers from epic latency while Surroundzone doesn't. Not a problem if you're field recording but if you're using the mic in the studio and you want the artists to hear themselves then it might well be worth having Surroundzone installed for that purpose if nothing else.

CC

Yes, it's a fair point. If used purely to post-process recordings then plugin latency obviously isn't an issue.

One way around the latency problem, though, is simply to split out the A-format capsules and mix them together in some convenient way for a real-time monitoring feed. It won't have the accurate directionality or stereo image attributes of the properly decoded signals of course, but it should be enough for live performance monitoring.

The guideline I was always taught years ago for working out where to place the SoundField mic was to listen to the omni (W) signal and use that to achieve an adequate direct/ambient sound balance. Summing the four A capsules will provide the same thing.

I'm told that the Rode plugin works in a very similar way to the Harpex one, and involves an 'upsampling' process (in terms of Ambisonic order, not sample rate) from the A-format signals way above standard B-format, and then decoding the required outputs from there. Hence the much more sophisticated maths and, presumably, the latency, but also the improved spatial accuracy and sound quality.